Depends in the powder... Less volume could create more pressure, and you could always adjust the OAL to compensate. But the extra bearing surface seems to be the key to the 35gr LF bullet's increase in velocity....

Which is why the Berger 30gr Var sucks wind. Don't get me wrong. It is a great bullet and can make for some nice 5.7 loads. BUT way to much bearing surface combined with a soft jacket keeps you from getting from getting the velocity you should from a 30gr bullet.

I see where you're coming from but then why are the NXT's getting better velocity than standard vmax style 35gr bullets? The 28gr SS195 bullets have more bearing surface and look how much better they are than traditional 30gr bullets?

Grantness wrote:Depends in the powder... Less volume could create more pressure, and you could always adjust the OAL to compensate. But the extra bearing surface seems to be the key to the 35gr LF bullet's increase in velocity....

Seems like you would want to be able to pack as much of the powder of your choice under the bullet as possible while keeping the pressures safe. Less bearing surface and more powder volume seem like a good way to do this. I do not claim to be any sort of expert or anything, I am VERY far from it :laugh: . I just came up with this by reasoning, I reserve the right to be wrong

Grantness wrote:I see where you're coming from but then why are the NXT's getting better velocity than standard vmax style 35gr bullets? The 28gr SS195 bullets have more bearing surface and look how much better they are than traditional 30gr bullets?

I don't recall any data posted with the NXT??? only the nosler FT 35gr.
Good point about the 28gr ss195.

Grantness wrote:I see where you're coming from but then why are the NXT's getting better velocity than standard vmax style 35gr bullets? The 28gr SS195 bullets have more bearing surface and look how much better they are than traditional 30gr bullets?

It's the core. When you shoot a bullet with a lead core, most folkes don't know this, the lead core becomes very soft semi fluid from the pressure and starts to flow. The acceleration/ G force also causes the now soften lead core to push back and bulge out the bottom of the bullet.

Thickness of jacket, hardness of the jacket and also hardness of the lead used to make the core all come into play.

With 28gr the copper jacket and aluminum core is much harder and is to a greater extent in a firearm cartridge immune to this phenomenon.

Just like the Barnes varmint grenade with it's compressed metal core it does not flow like the lead core variant and can be pushed more.

Grantness wrote:Depends in the powder... Less volume could create more pressure, and you could always adjust the OAL to compensate. But the extra bearing surface seems to be the key to the 35gr LF bullet's increase in velocity....

Seems like you would want to be able to pack as much of the powder of your choice under the bullet as possible while keeping the pressures safe. Less bearing surface and more powder volume seem like a good way to do this. I do not claim to be any sort of expert or anything, I am VERY far from it :laugh: . I just came up with this by reasoning, I reserve the right to be wrong

It is soo much more complicated than that ^

First of all, if you increase the bearing surface, then you can move to a slightly slower burning powder (in relation to the bullet weight), which would allow you to increase the charge and therefore get even more velocity out of your bullet (or course there are limits to this, dependent on the cartridge and gun design)

Next, in the 5.7 cartridge, almost all powders that work well are only running around 50-60 percent fill rates. So a longer bullet almost never impedes on the cases ability to hold powder.

Furthermore, since this is a blowback weapon, you need to consider timing - You have to generate just the right amount of pressure at just the right time otherwise everything will fail. The logic that makes sense in bolt guns and even semi auto gas type guns goes right out the window in a blowback. Thats also why some powders look good on paper but just dont work when you actually test them out.

VeTTeMaNC486 wrote:

Grantness wrote:I see where you're coming from but then why are the NXT's getting better velocity than standard vmax style 35gr bullets? The 28gr SS195 bullets have more bearing surface and look how much better they are than traditional 30gr bullets?

I don't recall any data posted with the NXT??? only the nosler FT 35gr.
Good point about the 28gr ss195.

I have posted data about the 35gr nosler lead free - and I will have a bunch of data about the 35gr NTX since I have a TON of them on the way

The longer bearing surface on the 28 gr bullet allows a slower burning powder (relatively speaking) to be used than would be typically possible if the bullet was a 28gr lead bullet.

For instance, If you had a 28gr lead bullet, the bullet would start leaving the case and would be started down the barrel faster than the 28gr ss195 does. This starts the ejection process sooner. It also allows less time for the case to build pressure, and less time for the case to properly "grip" the chamber.

What is so neat about the 28 gr bullet is that upon initial ignition the bullet is reacting similar to a 45-50 grain bullet in initial friction (because of the bearing surface) to get it going... However, once it starts moving, it gets going quickly because it is indeed only 28 grains. Therefore, You can use a slow(er) burning powder than would typically be possible with a lead 28gr design. Also, because it is a 28gr bullet you can use more of the slower burning powder (relatively speaking) than you can with a 40+ grain bullet. The combination of the previous two items gives just the right timing and pressure and charge to get the 28gr cooking...

The 40gr vmax is kind of just the opposite of the above - the bullet has more weight, but has a very small bearing surface. It has less friction, but takes more intertia to get it going... It turns out that the bearing surface/weight ratio coupled with the proper powder makes the 40gr vmax one of (if not the) top choice for the 5.7 cartridge.

What remains to be seen is how the 35 gr NTX bullet weight/bearing surface ratio works in the 5.7 - It may work great, or it may be just ok. We will see...

Plus this makes a difference as well (the info below), since the bullets react differently in their "fluid" movement down the barrel

panzermk2 wrote:
It's the core. When you shoot a bullet with a lead core, most folkes don't know this, the lead core becomes very soft semi fluid from the pressure and starts to flow. The acceleration/ G force also causes the now soften lead core to push back and bulge out the bottom of the bullet.

Thickness of jacket, hardness of the jacket and also hardness of the lead used to make the core all come into play.

With 28gr the copper jacket and aluminum core is much harder and is to a greater extent in a firearm cartridge immune to this phenomenon.

Just like the Barnes varmint grenade with it's compressed metal core it does not flow like the lead core variant and can be pushed more.

Its complicated. But at the same time the physics behind it all is really interesting.

I wrote a LOT - i will have to re-read this later and make sure there aren't any typos :laugh:

Grantness wrote:Depends in the powder... Less volume could create more pressure, and you could always adjust the OAL to compensate. But the extra bearing surface seems to be the key to the 35gr LF bullet's increase in velocity....

Seems like you would want to be able to pack as much of the powder of your choice under the bullet as possible while keeping the pressures safe. Less bearing surface and more powder volume seem like a good way to do this. I do not claim to be any sort of expert or anything, I am VERY far from it :laugh: . I just came up with this by reasoning, I reserve the right to be wrong

It is soo much more complicated than that ^

First of all, if you increase the bearing surface, then you can move to a slightly slower burning powder (in relation to the bullet weight), which would allow you to increase the charge and therefore get even more velocity out of your bullet (or course there are limits to this, dependent on the cartridge and gun design)

Next, in the 5.7 cartridge, almost all powders that work well are only running around 50-60 percent fill rates. So a longer bullet almost never impedes on the cases ability to hold powder.

Furthermore, since this is a blowback weapon, you need to consider timing - You have to generate just the right amount of pressure at just the right time otherwise everything will fail. The logic that makes sense in bolt guns and even semi auto gas type guns goes right out the window in a blowback. Thats also why some powders look good on paper but just dont work when you actually test them out.

VeTTeMaNC486 wrote:

Grantness wrote:I see where you're coming from but then why are the NXT's getting better velocity than standard vmax style 35gr bullets? The 28gr SS195 bullets have more bearing surface and look how much better they are than traditional 30gr bullets?

I don't recall any data posted with the NXT??? only the nosler FT 35gr.
Good point about the 28gr ss195.

I have posted data about the 35gr nosler lead free - and I will have a bunch of data about the 35gr NTX since I have a TON of them on the way

The longer bearing surface on the 28 gr bullet allows a slower burning powder (relatively speaking) to be used than would be typically possible if the bullet was a 28gr lead bullet.

For instance, If you had a 28gr lead bullet, the bullet would start leaving the case and would be started down the barrel faster than the 28gr ss195 does. This starts the ejection process sooner. It also allows less time for the case to build pressure, and less time for the case to properly "grip" the chamber.

What is so neat about the 28 gr bullet is that upon initial ignition the bullet is reacting similar to a 45-50 grain bullet in initial friction (because of the bearing surface) to get it going... However, once it starts moving, it gets going quickly because it is indeed only 28 grains. Therefore, You can use a slow(er) burning powder than would typically be possible with a lead 28gr design. Also, because it is a 28gr bullet you can use more of the slower burning powder (relatively speaking) than you can with a 40+ grain bullet. The combination of the previous two items gives just the right timing and pressure and charge to get the 28gr cooking...

The 40gr vmax is kind of just the opposite of the above - the bullet has more weight, but has a very small bearing surface. It has less friction, but takes more intertia to get it going... It turns out that the bearing surface/weight ratio coupled with the proper powder makes the 40gr vmax one of (if not the) top choice for the 5.7 cartridge.

What remains to be seen is how the 35 gr NTX bullet weight/bearing surface ratio works in the 5.7 - It may work great, or it may be just ok. We will see...

Plus this makes a difference as well (the info below), since the bullets react differently in their "fluid" movement down the barrel

panzermk2 wrote:
It's the core. When you shoot a bullet with a lead core, most folkes don't know this, the lead core becomes very soft semi fluid from the pressure and starts to flow. The acceleration/ G force also causes the now soften lead core to push back and bulge out the bottom of the bullet.

Thickness of jacket, hardness of the jacket and also hardness of the lead used to make the core all come into play.

With 28gr the copper jacket and aluminum core is much harder and is to a greater extent in a firearm cartridge immune to this phenomenon.

Just like the Barnes varmint grenade with it's compressed metal core it does not flow like the lead core variant and can be pushed more.

Its complicated. But at the same time the physics behind it all is really interesting.

I wrote a LOT - i will have to re-read this later and make sure there aren't any typos :laugh:

You really need to understand a great deal of physics, engineering, and sounds like even fluid dynamics to wrap your mind around this stuff. For those of us not smart enough to get everything (including me :laugh: )...we can always keep up the trial and error testing. It works.....eventually. Never underestimate the power of empirical evidence

i planned on testing w/ full power too actually... using the T/C. Im almost afraid to try any 296 loads out of the FsN. We'll see. I took my trimmer apart a while back to use the electric drill I had on there....so most of the brass I have ready is T/C only brass. I'll try to get my trimmer up and running shortly and work on that 296 stuff...

Grantness wrote:You really need to understand a great deal of physics, engineering, and sounds like even fluid dynamics to wrap your mind around this stuff. For those of us not smart enough to get everything (including me :laugh: )...we can always keep up the trial and error testing. It works.....eventually. Never underestimate the power of empirical evidence

Be safe :thumb:

We don't really learn much about that kinda stuff in my Electrical Engineering classes :laugh: . (Which I am finally starting to get into after taking so many freaking core classes/pre-reqs... 2 more years and counting... ).

iFire, if you do not mind, could you post a picture of the projectiles in question side by side (40gr vmax, 35gr nlf, 35gr nxt, and possibly the 28gr ss195), it would probably go well with our discussion.

Grantness wrote:i planned on testing w/ full power too actually... using the T/C. Im almost afraid to try any 296 loads out of the FsN. We'll see. I took my trimmer apart a while back to use the electric drill I had on there....so most of the brass I have ready is T/C only brass. I'll try to get my trimmer up and running shortly and work on that 296 stuff...

Dont worry about the 296 subs in the FsN - I'll take care of it... I am going to shoot a bunch more probably tomorrow and I'll post the results including all the relevant SD, ES and Average numbers...

Grantness wrote:i planned on testing w/ full power too actually... using the T/C. Im almost afraid to try any 296 loads out of the FsN. We'll see. I took my trimmer apart a while back to use the electric drill I had on there....so most of the brass I have ready is T/C only brass. I'll try to get my trimmer up and running shortly and work on that 296 stuff...

Dont worry about the 296 subs in the FsN - I'll take care of it... I am going to shoot a bunch more probably tomorrow and I'll post the results including all the relevant SD, ES and Average numbers...

Looking forward to it. Seems to go completely against "they" say about 296. I can't say I have ever heard of 296/h110 being used in anything resembling a reduced load :laugh:

For subs are you just going to use just 55gr fmjs or have you considered trying something heavier, like a 62gr fmj? Not sure how well those would stabilize...

VeTTeMaNC486 wrote:
We don't really learn much about that kinda stuff in my Electrical Engineering classes :laugh: . (Which I am finally starting to get into after taking so many freaking core classes/pre-reqs... 2 more years and counting... ).

iFire, if you do not mind, could you post a picture of the projectiles in question side by side (40gr vmax, 35gr nlf, 35gr nxt, and possibly the 28gr ss195), it would probably go well with our discussion.

3 years of Various Physics, 2 years of BioChemistry, 4 years of Physical Chemistry and 2 years of Organic Chemistry - Im glad college is just a memory now for me...

Good luck with your final 2 years :p

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I have Lots of .224 bullets, including the few you mentioned - when i get the NTX's i will post a pic of as many of them as possible in a neat little line...